Dual crankshaft engine

Abstract

A dual-crankshaft engine is presented. In one embodiment, the engine includes a first crankshaft and a second crankshaft. The second crankshaft is coupled with the first crankshaft such that the first crankshaft and the second crankshaft are horizontally coplanar. The engine further includes a first piston that is operable to reciprocate in a first horizontal cylinder via coupling with the first crankshaft, and a second piston that is operable to reciprocate in a second horizontal cylinder via coupling with the second crankshaft. The second horizontal cylinder is horizontally collinear with and opposing the first horizontal cylinder.

The invention claimed is: 
     
       1. An engine comprising:
 a first crankshaft; 
 a second crankshaft coupled with the first crankshaft such that the first crankshaft and the second crankshaft are coplanar; 
 a first piston operable to reciprocate in a first cylinder via coupling with the first crankshaft; and 
 a second piston operable to reciprocate in a second cylinder via coupling with the second crankshaft, the second cylinder being opposing and collinear with the first cylinder, and a centerline of the cylinders being parallel to a plane of the crankshafts. 
 
     
     
       2. The engine of  claim 1 , wherein the first piston is top dead center in the first cylinder when the second piston is top dead center in the second cylinder. 
     
     
       3. The engine of  claim 1 , wherein the first and second crankshafts are mechanically coupled such that the second crankshaft rotates in an opposite direction from the first crankshaft. 
     
     
       4. The engine of  claim 1 , wherein a centerline of the first crankshaft, a centerline of the second crankshaft, a centerline of the first cylinder, and a centerline of the second cylinder are all coplanar. 
     
     
       5. The engine of  claim 1 , wherein a centerline of the first crankshaft and a centerline of the second crankshaft are coplanar in a first plane, and a centerline of the first cylinder and a centerline of the second cylinder are coplanar in a second plane that is parallel to and offset from the first plane. 
     
     
       6. The engine of  claim 1 , further comprising:
 a transmission that is coupled to the first crankshaft or the second crankshaft, and the first crankshaft and the second crankshaft include thrust control bearings that oppose axial gear forces from the first and second crankshafts and from the transmission. 
 
     
     
       7. The engine of  claim 1 , wherein a moment of inertia of the first crankshaft along with a first mechanism that is coupled tightly with the first crankshaft to rotate in the same direction as the first crankshaft is equivalent to a moment of inertia of the second crankshaft along with a second mechanism that is coupled tightly with the second crankshaft to rotate in the same direction as the second crankshaft. 
     
     
       8. The engine of  claim 1 , wherein the first cylinder fires at a different time than the second cylinder. 
     
     
       9. The engine of  claim 1 , further comprising:
 a third piston operable to reciprocate in a third cylinder via coupling with the first crankshaft; and 
 a fourth piston operable to reciprocate in a fourth cylinder via coupling with the second crankshaft, the fourth cylinder being opposing and collinear with the third cylinder, and the first piston being top dead center in the first cylinder and the second piston being top dead center in the second cylinder when the third piston is bottom dead center in the third cylinder and the fourth piston is bottom dead center in the fourth cylinder. 
 
     
     
       10. An engine comprising:
 a first crankshaft; 
 a second crankshaft coupled with the first crankshaft such that the first crankshaft and the second crankshaft axes of rotation are coplanar and the second crankshaft rotates in an opposite direction from the first crankshaft; 
 a first piston operable to reciprocate in a first cylinder via coupling with the first crankshaft; 
 a second piston operable to reciprocate in a second cylinder via coupling with the first crankshaft; 
 a third piston operable to reciprocate in a third cylinder via coupling with the first crankshaft; 
 a fourth piston operable to reciprocate in a fourth cylinder via coupling with the first crankshaft; 
 a fifth piston operable to reciprocate in a fifth cylinder via coupling with the second crankshaft; 
 a sixth piston operable to reciprocate in a sixth cylinder via coupling with the second crankshaft; 
 a seventh piston operable to reciprocate in a seventh cylinder via coupling with the second crankshaft; and 
 an eighth piston operable to reciprocate in an eighth cylinder via coupling with the second crankshaft, wherein the first piston is top dead center in the first cylinder and the second piston is top dead center in the second cylinder when the third piston is bottom dead center in the third cylinder and the fourth piston is bottom dead center in the fourth cylinder, and with ninety degrees of rotation of the crankshafts, the fifth piston is top dead center in the fifth cylinder and the sixth piston is top dead center in the sixth cylinder when the seventh piston is bottom dead center in the seventh cylinder and the eighth piston is bottom dead center in the eighth cylinder. 
 
     
     
       11. The engine of  claim 10 , wherein centerlines of the first, second, third, and fourth cylinders are coplanar with each other and with a centerline of the first crankshaft in a first plane, centerlines of the fifth, sixth, seventh, and eighth cylinders are coplanar with each other and with a centerline of the second crankshaft in a second plane that is parallel with the first plane; and the centerlines of the first and second crankshafts are coplanar in a third plane that is perpendicular to the first and second planes. 
     
     
       12. The engine of  claim 10 , wherein centerlines of the first, second, third, fourth, fifth, sixth, seventh, and eighth cylinders are parallel to each other, and perpendicular to a plane including a centerline of the first crankshaft and a centerline of the second crankshaft, and the centerlines of the first, second, third, fourth, fifth, sixth, seventh, and eighth cylinders being offset from and not intersecting the centerlines of the first and second crankshafts. 
     
     
       13. The engine of  claim 10 , wherein one or more cylinders are deactivated at part load or no load operating conditions. 
     
     
       14. The engine of  claim 10 , further comprising:
 a first cylinder head coupled to the first, third, fifth, and seventh cylinders, the first cylinder head forming a first exhaust manifold shared between the first, third, fifth, and seventh cylinders, and positioned below the first and third cylinders and above the fifth and seventh cylinders; and 
 a second cylinder head coupled to the second, fourth, sixth, and eighth cylinders, the second cylinder head forming a second exhaust manifold shared between the second, fourth, sixth, and eighth cylinders, and positioned below the second and fourth cylinders and above the fourth and eighth cylinders. 
 
     
     
       15. The engine of  claim 10 , wherein the first crankshaft includes a first helical gear set that is rotatable in a first direction, and the second crankshaft includes a second helical gear set that is rotatable in a second direction that opposes the first direction.